Dapagliflozin benefits low-EF heart failure regardless of diuretic dose: DAPA-HF

FROM ESC HEART FAILURE 2020

 

The DAPA-HF trial has already changed cardiology in opening up a new class of drugs to patients with heart failure (HF), whether or not they have diabetes. Now the trial is yielding clues as to how it benefits them. For now, it’s doing so by process of elimination.A new analysis suggests that dapagliflozin (Farxiga, AstraZeneca) didn’t need help from loop diuretics to cut the risk for clinical events in patients with HF with reduced ejection fraction (HFrEF), a benefit seen across the spectrum of glycosylated hemoglobin levels and without compromising renal function, said DAPA-HF investigators. Also, use of dapagliflozin and its clinical effects were not associated with changes in loop diuretic dosage. Those findings and others suggest the drug helps in HFrEF at least partly by some other mechanism than its own diuretic effect, the researchers say.Such insights will likely be important to case-by-case decisions on whether to use the drug, a sodium-glucose cotransporter 2 (SGLT2) inhibitor once reserved for patients with diabetes, given the recently broader landscape of HF treatment options.As previously reported from DAPA-HF, with more than 4,700 patients, those who received dapagliflozin showed significant reductions in the primary end point, a composite of cardiovascular (CV) death, HF hospitalization, and urgent HF visit requiring IV therapy over about 18 months. The 45% of patients with and 55% without type 2 diabetes enjoyed about equal benefit in the placebo-controlled trial for that end point, as well as for all-cause mortality.

SGLT2 inhibitors work in diabetes by promoting urinary glucose excretion. That had led some to speculate that its benefit in HFrEF comes primarily from a diuretic effect; the current findings largely put that question to rest.

“Our findings show that treatment with dapagliflozin was effective regardless of diuretic use or diuretic dose. They also show that dapagliflozin did not lead to an increase in renal adverse events or discontinuation of therapy in patients treated with a diuretic,” trialist Alice M. Jackson, MB, ChB, said in an interview.

“In fact, renal adverse events were generally less common in patients treated with dapagliflozin, across the diuretic categories,” said Dr. Jackson, from the University of Glasgow.

Dr. Jackson presented the new analysis at a Late-Breaking Science Session during the European Society of Cardiology Heart Failure Discoveries virtual meeting. The HFA sessions were conducted virtually this year due to the COVID-19 pandemic.

At baseline, 84% of patients were on conventional diuretics. The post hoc analysis broke out all patients by loop-diuretic dosage level: none; less than 40 mg equivalents (FE); 40 mg FE; or more than 40 mg FE. Clinical outcomes were similar across the four groups.

Clinicians in the trial “were not given specific advice about adjusting diuretic doses, but were encouraged to assess volume status and make changes to medical therapy based on this, if necessary,” Dr. Jackson said. “This suggests that, for most patients, starting dapagliflozin will not necessitate a change in diuretic dose.”

With the caveat that the event rate was low in the relatively few patients not prescribed loop diuretics, she said, “the magnitude of the benefit from dapagliflozin appeared to be larger in patients not treated with a diuretic.”

There was no suggestion of a diuretic dose–response effect or statistical interaction between diuretic use and clinical outcomes on dapagliflozin, Dr. Jackson observed in the interview.

Of note in the analysis, hematocrit levels shot up soon after patients started active therapy, but they didn’t rise much in the placebo group. The sustained hematocrit elevation on dapagliflozin, seen at all diuretic dosage levels, persisted even after dosage reductions at 6 months, she said.

“Dapagliflozin is effective in HFrEF irrespective of background diuretic therapy; therefore, it is almost certainly not purely acting as a diuretic,” Andrew J. Coats, MD, DSc, MBA, said in an interview.

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